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The structure that results is a cross-strand exchange, also known as a Holliday junction. The contact between two chromatids that will soon undergo crossing-over is known as a chiasma . The Holliday junction is a tetrahedral structure which can be 'pulled' by other recombinases, moving it along the four-stranded structure.
Cross-bridge theory states that actin and myosin form a protein complex (classically called actomyosin) by attachment of myosin head on the actin filament, thereby forming a sort of cross-bridge between the two filaments. The sliding filament theory is a widely accepted explanation of the mechanism that underlies muscle contraction.
Two models of nuclear congression have been proposed: the sliding cross-bridge, and the plus end model. In the sliding cross-bridge model, the microtubules run antiparallel to each other for the entire distance between the two pronuclei, forming cross-links to each other, and each attaching to the opposite nucleus at the plus end. This is the ...
Chromatin bridge is a mitotic occurrence that forms when telomeres of sister chromatids fuse together and fail to completely segregate into their respective daughter cells. Because this event is most prevalent during anaphase , the term anaphase bridge is often used as a substitute.
Cytological markers of BFB-cycle-mediated chromosomal instability: "budding" nuclei (A, C, D) and partly fragmented nucleus with double nucleoplasmic bridge (B). [1] Breakage-fusion-bridge (BFB) cycle (also breakage-rejoining-bridge cycle) is a mechanism of chromosomal instability, discovered by Barbara McClintock in the late 1930s. [2] [3]
Cross-bridge cycle. Cross-bridge cycling is a sequence of molecular events that underlies the sliding filament theory. A cross-bridge is a myosin projection, consisting of two myosin heads, that extends from the thick filaments. [1] Each myosin head has two binding sites: one for adenosine triphosphate (ATP) and another for actin.
The CO type of recombination involves the intermediate formation of two "Holliday junctions" indicated in the lower right of the figure by two X-shaped structures in each of which there is an exchange of single strands between the two participating chromatids. This pathway is labeled in the figure as the DHJ (double-Holliday junction) pathway.
The two pathways for homologous recombination in eukaryotes, showing the formation and resolution of Holliday junctions. The Holliday junction is a key intermediate in homologous recombination, a biological process that increases genetic diversity by shifting genes between two chromosomes, as well as site-specific recombination events involving integrases.